Re: I just discovered an alternative use of the `in`-operator

[Paul Backus via Digitalmars-d-learn]

On Thursday, 6 August 2020 at 21:50:06 UTC, Per Nordlöw wrote:

I just discovered that the is-operator can be used as in

template ElementType(R)
{
    static if (is(typeof(R.init.front.init) T))
        alias ElementType = T;
    else
        alias ElementType = void;
}

. Very powerful. Is this documented?

Yes, in the following paragraph under "IsExpression" [1]:

Identifier is declared to be an alias of the resulting type if the condition is satisfied. The Identifier forms can only be used if the IsExpression appears in a StaticIfCondition.

[1] https://dlang.org/spec/expression.html#is_expression